As the performance of semiconductor apparatuses is improved, it becomes increasingly important to control contaminations during a fabrication process of such semiconductor apparatuses. For example, when a silicon (Si) substrate related to a semiconductor fabrication is contaminated, sometimes it happens that devices formed in the silicon substrate do not have sufficient characteristics for a required performance, and a yield of the semiconductor apparatus manufactured becomes lower. For example, as to detecting contaminations on a silicon (Si) substrate, there is a known method in which a solvent, such as hydrogen fluoride (HF) is dripped down onto the Si substrate for dissolving metal contaminants, and the solution is analyzed by an inductively coupled plasma mass spectroscopy (ICP-MS) method.
FIG. 1A-FIG. 1D are illustrative drawings showing an analysis method for analyzing metal contamination on a Si substrate 1. A process step is shown in FIG. 1B, for example, where a solution including HF is dripped down onto a Si substrate 1. Next, in the process steps shown in FIG. 1C-FIG. 1D, a spherical droplet 2 of the solution obtained by dripping is rolled over on the substrate 1, and it dissolves metals on the substrate.
In the next step, the solution 2 containing contaminant substances such as metal and the like, is collected. The solution 2 may then be analyzed using for example the ICP-MS method, so that metallic contaminations on the Si substrate can be qualitatively or quantitatively analyzed.
Patent Reference 1 Japanese Patent Application Publication No. 8-237709.
However, when a film is formed on an object to be analyzed on a silicon (Si) substrate, there is difficulty to apply the above analysis method.
FIG. 2A is an illustrative drawing showing a Si substrate 1 to be analyzed and a film 3 formed on the Si substrate 1. When the film 3 is formed on the Si substrate 1, it becomes difficult to dissolve metal on the Si substrate 1 by using a solution.
For example, in a plasma etching process using fluorocarbon related gas (CF4, CHF3, and the like), a film of fluorocarbon related substances may form on a substrate. Such fluorocarbon related film has a property of low solubility against a HF (hydrofluoric acid) related solution (or a vapor of HF) . Therefore, it is difficult to analyze contamination of a substrate processed with plasma etching equipment.
Further, as a surface of a fluorocarbon related film including oxygen atoms has lower wettability (larger hydrophilicity) than that of a Si surface, as shown in FIG. 2B, when a droplet of a solution 2 is dropped onto the film surface, the solution spreads over the film surface, so that it becomes difficult to roll over the droplet on the film surface.
In addition, for removing the film, when a plasma etching process or a sputtering process is performed on the substrate, contaminant materials can disperse. Moreover another contaminant material can be generated, making it difficult to maintain the accuracy of the analysis.